A Humpback whale breaks the surface as it heads south to Antarctica for the summer.

It’s all too rare to see governments making decisions that are actually in line with science. But September ended very well. The UK government announced its support for protecting 30% of the world’s oceans by 2030. That’s the level of ambition that scientists tell us is needed to protect marine wildlife and tackle climate change. So this is a really big deal!

Greenpeace have been calling for at least a third of the world’s oceans to be protected by 2030. This announcement helps set the bar for what we, as an global community, need to do over the next decade.

As ever, this isn’t job done. Far too often targets are set, and then pass by unmet. The future of our oceans is far too important to suffer that same fate. We need to make sure ministers start meeting this bold pledge – and fast.

That’s why our global oceans need a Global Ocean Treaty.

The oceans beyond borders, aka the high seas, cover more space than all the continents combined. They contain ancient coral reefs and trenches deep enough to hold Mount Everest.

These vast blue worlds are the highways for whales, turtles and tuna travelling thousands of miles. Scientists reckon the global oceans are home to greater biodiversity than even the tropical rainforests.

And there’s so much more that haven’t even discovered yet. The high seas are the least explored part of the Earth, with only 0.0001% (yes, that many zeros) of its seafloor so far investigated by scientists. It’s common to hear marine biologists say that we know more about the dark side of the Moon than the deep global oceans.

But the global oceans are under threat. Current ocean law focuses more on the right to exploit these waters than on any duty to protect them. We only have to look at the state of oceans to see that the status quo is not working.

To turn the tide, we need a strong Global Ocean Treaty. And to protect at least 30% of our oceans by 2030, we need a global network of ocean sanctuaries. Ocean sanctuaries put an area off-limits to extractive activity, providing a haven for marine life to recover from multiple threats and build resilience to ongoing pressures like warming and acidifying waters.

We know that ocean sanctuaries work: in and around them, we find more wildlife, bigger creatures and greater diversity of life. Seas that are thriving with life can store more carbon and help to underpin global food security – benefitting us all.

Right now, only around 4% of the oceans are protected in sanctuaries and less than 1% of the high seas. Getting to 30% protection over the next 12 years is a big gap to fill. But last month, governments came together at the United Nations to discuss this new Global Ocean Treaty.

Governments have set themselves the deadline of 2020 to agree this landmark treaty. With public support for ocean conservation surging in the wake of Blue Planet II and concern over plastic pollution, politicians like Michael Gove couldn’t hope for a stronger mandate to think big.

In fact, over 2 million people worldwide are calling on governments to move faster, boosting these UN negotiations by protecting the few areas of international waters that they already can.